Cancer is considered to be a complex disease state often involving multiple mechanisms through which growth of the cells of a particular organ or tissue in the body go beyond control. Usually, cancer and cancer cells take their name according to the tissue in which the disease originates. Breast cancer is the leading cause of mortality among women resulting in more than half a million deaths worldwide every year. It is the second leading cause of cancer-related deaths in women today and is the most common cancer among women excluding non-melanoma skin cancers. An estimated 252,710 new cases of invasive breast cancer were expected to be diagnosed in women in the U.S alone, along with 63,410 new cases of non-invasive (in situ) breast cancer in the year 2017 (Siegel et al., (2017). Cancer Stats 67: 7-30). In 2017, approximately 40,610 women were expected to die from breast cancer. Estrogen receptor (ER), Progesterone receptor (PR) and their associated steroid hormones, play important roles in the development, differentiation, function and growth of normal breast and endometrial cells. ERs are attractive targets in the treatment of breast cancer as they are over-expressed in breast cancer cells. Certain molecules that are selective, non-steroidal and anti-estrogenic products, commonly called Selective Estrogen Receptor Modulators (SERMs) serve as potential alternatives in the treatment of hormone-dependent ER(+) breast cancer (Maximov et al., (2013) Curr. Clin. Pharmacol. 8:135-155; Jordan V C. (2007) Nat. Revs. Cancer 7: 46-53).
Tetrahydroisoquinoline natural products have shown to exhibit important biological activities that make them essential targets for drug discovery. The tetrahydroisoquinoline family of alkaloids includes potent cytotoxic agents that display a range of biological properties such as antitumor and antimicrobial activities. They were studied thoroughly over a period of more than 40 years, starting with the isolation of naphthyndinomycin in 1974 (Buckingham J B. (1996) Dictionary of Natural Products. Vol. 9. Chapman and Hall; USA). 1-Methyl-I, 2, 3, 4-tetrahydraisoquinoline (1-MeTIQ) is considered to be a possible endogenous Parkinsonism-preventing agent and a neuro-protectant. Its ability to antagonize the behavioral syndrome produced by well-known neurotoxins is well documented (Ohta et al., (1990) Basic, Clinical and Therapeutical Aspects of Alzheimer's and Parkinson's Diseases, Vol. 1. Plenum Press, N. York).